Exposure Condition Setting Method, Substrate Processing Device, and Computer Program

ABSTRACT

A method includes forming a resist film on an etching target layer disposed on a test substrate, and performing sequential light exposure with a predetermined test pattern on the resist film sequentially at a plurality of areas, while respectively using different combinations of a light exposure amount and a focus value, along with subsequent development, thereby forming resist patterns at the plurality of areas; then etching the etching target layer, removing the resist patterns, and measuring shapes of etched patterns at the plurality of areas by means of a scatterometory technique; and determining a management span of combinations of a light exposure amount and a focus value admissible to obtain an etched pattern with a predetermined shape, with reference to the light exposure amounts and focus values used in the sequential light exposure, the line widths of the resist patterns, and the line widths of the etched patterns.

TECHNICAL FIELD

The present invention relates to a light exposure condition settingmethod for setting optimum light exposure conditions for performinglight exposure with a predetermined pattern on a resist film to be usedas an etching mask, to form an etched pattern in a well controlled shapein the process of manufacturing semiconductor devices. The presentinvention further relates to a substrate processing apparatus and acomputer program each used in performing the light exposure conditionsetting method.

BACKGROUND ART

In the process of manufacturing semiconductor devices havingmulti-layered interconnection structures, such as a damascene structure,the following steps are performed, for example. Specifically, a resistfilm is formed on an inter-level insulating film, and is then subjectedto light exposure with a predetermined pattern and development.Thereafter, the resist pattern thus formed is used as an etching maskfor performing plasma etching on the inter-level insulating film,thereby patterning the inter-level insulating film. Also in the processof fabricating a photo-mask, a resist pattern is formed on a lightshielding layer disposed on a substrate, and dry etching is thenperformed thereon, thereby patterning the light shielding layer.

In order to control the line width and so forth of an etched patternthus formed, the shapes of etched patterns are periodically observed byan SEM, as disclosed in Patent Document 1 set out below. Where the shapeof an etched pattern is out of a predetermined dimension range, etchingconditions and process conditions (the light exposure amount and focusvalue) in a photolithography step for forming a resist pattern to beused as an etching mask are adjusted by an operator, on the basis ofpast process data or the like, thereby correcting dimensions of etchedpatterns.

However, since SEM observation requires skill and entails individualdifferences in judging shapes, it takes a long time to determine lightexposure conditions. Further, according to the dimension correctingmethod described above, dimensions of etched patterns are adjusted inaccordance with the average dimensions in one wafer (or one lot), andthus planar fluctuations of dimensions on one wafer cannot be corrected.

[Patent Document 1]

Jpn. Pat. Appln. KOKAI Publication No. 2003-59990

DISCLOSURE OF INVENTION

An object of the present invention is to provide a light exposurecondition setting method that allows an etched pattern with apredetermined shape to be easily obtained.

Another object of the present invention is to provide a light exposurecondition setting method that allows etched patterns with apredetermined shape all over the surface of a substrate.

Another object of the present invention is to provide a substrateprocessing apparatus and a computer program each used in performing thelight exposure condition setting method.

According to a first aspect of the present invention, there is provideda light exposure condition setting method comprising: forming a resistfilm on an etching target layer disposed on a test substrate, andperforming sequential light exposure with a predetermined test patternon the resist film sequentially at a plurality of areas, whilerespectively using different combinations of a light exposure amount anda focus value, along with subsequent development, thereby forming resistpatterns at the plurality of areas; measuring shapes of the resistpatterns at the plurality of areas by means of a scatterometorytechnique; etching the etching target layer by use of the resist filmwith the resist patterns formed thereon as an etching mask, and removingthe resist film from the substrate, thereby forming etched patterns atthe plurality of areas; measuring shapes of the etched patterns at theplurality of areas by means of a scatterometory technique; anddetermining a management span of combinations of a light exposure amountand a focus value admissible to obtain an etched pattern with apredetermined shape, with reference to the combinations of a lightexposure amount and a focus value used in the sequential light exposurefor the plurality of areas, measurement results of the shapes of theresist patterns formed at the plurality of areas, and measurementresults of the shapes of the etched patterns formed at the plurality ofareas.

In the first aspect described above, the method may further comprise:determining one combination of a light exposure amount and a focus valuewithin the management span after determining the management span;forming a resist film on an etching target layer disposed on a productsubstrate, and performing light exposure with a predetermined productpattern on the resist film, while using the combination of a lightexposure amount and a focus value thus determined, along with subsequentdevelopment; and etching the etching target layer and removing theresist film, thereby forming an etched pattern; measuring a shape of theetched pattern by means of a scatterometory technique; judging whetheror not the shape of the etched pattern is within a predeterminedadmissible dimension range; and, if the shape of the etched pattern isout of the admissible dimension range, determining a new combination ofa light exposure amount and a focus value within the management spansuch that a shape of an etched pattern to be formed on another productsubstrate subsequently processed is brought into the admissibledimension range.

In the first aspect described above, the method may further comprise:determining one combination of a light exposure amount and a focus valuewithin the management span after determining the management span;forming a resist film on an etching target layer disposed on a productsubstrate, and performing light exposure with a predetermined productpattern on the resist film, while using the combination of a lightexposure amount and a focus value thus determined, along with subsequentdevelopment; and etching the etching target layer and removing theresist film, thereby forming an etched pattern; measuring a shape of theetched pattern by means of a scatterometory technique; judging whetheror not the shape of the etched pattern is within a predeterminedadmissible dimension range; if the shape of the etched pattern formed onthe product substrate is out of the predetermined admissible dimensionrange, and a new combination of a light exposure amount and a focusvalue, determined such that a shape of an etched pattern to be formed onanother product substrate subsequently processed is brought into theadmissible dimension range, is out of the management span, performinglight exposure with the product pattern on said another productsubstrate, while using the new combination of a light exposure amountand a focus value thus determined, along with subsequent development;and measuring a shape of a resist pattern thereby obtained; if the shapeof the resist pattern is within a predetermined dimension range,determining a new management span of combinations of a light exposureamount and a focus value, with reference to a target dimension of thetest pattern, the shapes of the resist patterns formed on the testsubstrate, and the combinations of a light exposure amount and a focusvalue used in the sequential light exposure; and, if the shape of theresist pattern is out of a predetermined dimension range, re-executing aseries of processes to determine a new management span of combinationsof a light exposure amount and a focus value, while using a new testsubstrate.

In this case, in order to determine the new management span, while usingthe new test substrate, the method preferably further comprises, priorto processing the new test substrate, checking apparatuses used for aseries of processes from resist film formation through an etchingprocess to resist film removal.

In the first aspect described above, the plurality of areas preferablyform a matrix with a light exposure amount and a focus value used asparameters, and a measurement target of a pattern preferably includes aline width of the pattern.

According to a second aspect of the present invention, there is provideda substrate processing apparatus comprising: a light exposure processingsection configured to perform light exposure with a predeterminedpattern on a resist film formed on an etching target layer disposed on asubstrate; a pattern shape measuring section configured to measure ashape of a resist pattern and a shape of an etched pattern by means of ascatterometory technique; and a control section configured to controlthe light exposure processing section and the pattern shape measuringsection, wherein the control section makes reference to: a result ofperforming sequential light exposure with a predetermined test patternon a resist film formed on a substrate, sequentially at a plurality ofareas, while respectively using different combinations of a lightexposure amount and a focus value, along with subsequent development,thereby forming resist patterns at the plurality of areas, and thenmeasuring shapes of the resist patterns at the plurality of areas by thepattern shape measuring section; a result of etching the etching targetlayer by use of the resist film with the resist patterns formed thereonas an etching mask, thereby forming etched patterns at the plurality ofareas, and then measuring shapes of the etched patterns at the pluralityof areas by the pattern shape measuring section; and the combinations ofa light exposure amount and a focus value used in the sequential lightexposure for the plurality of areas, so as to determine a managementspan of combinations of a light exposure amount and a focus valueadmissible to obtain a predetermined etched pattern.

In the second aspect described above, the apparatus may have anarrangement in which, if a shape of an etched pattern formed on aproduct substrate by performing light exposure thereon, while using onecombination of a light exposure amount and a focus value determinedwithin the management span, is out of the admissible dimension range,the control section determines a new combination of a light exposureamount and a focus value within the management span such that a shape ofan etched pattern to be formed on another product substrate subsequentlyprocessed is brought into the admissible dimension range.

In the second aspect described above, the apparatus may have anarrangement in which, if a shape of an etched pattern formed on aproduct substrate by performing light exposure thereon, while using onecombination of a light exposure amount and a focus value determinedwithin the management span, is out of the admissible dimension range,and a new combination of a light exposure amount and a focus value,determined such that a shape of an etched pattern to be formed onanother product substrate subsequently processed is brought into theadmissible dimension range, is out of the management span, the controlsection controls the light exposure processing section to perform lightexposure on said another product substrate, while using the newcombination of a light exposure amount and a focus value thusdetermined, and, if a shape of a resist pattern formed on said anotherproduct substrate by performing light exposure thereon, while using thenew combination of a light exposure amount and a focus value, is withina predetermined dimension range, the control section determines a newmanagement span of combinations of a light exposure amount and a focusvalue, with reference to the shapes of the resist patterns formed on thesubstrate by the sequential light exposure, a target dimension of aphoto mask used for forming the resist patters, and the combinations ofa light exposure amount and a focus value used in the sequential lightexposure.

In the second aspect described above, the pattern shape measuringsection may include a first measuring section configured to measure ashape of a resist pattern and a second measuring section configured tomeasure a shape of an etched pattern.

According to a third aspect of the present invention, there is provideda computer program including software for execution on a computer, usedfor a substrate processing apparatus, which comprises a light exposureprocessing section configured to perform light exposure with apredetermined pattern on a resist film formed on a substrate, and apattern shape measuring section configured to measure a shape of aresist pattern and a shape of an etched pattern by means of ascatterometory technique, wherein the software, when executed by thecomputer, controls the apparatus to perform a method comprising: forminga resist film on an etching target layer disposed on a test substrate,and performing sequential light exposure with a predetermined testpattern on the resist film sequentially at a plurality of areas, whilerespectively using different combinations of a light exposure amount anda focus value, along with subsequent development, thereby forming resistpatterns at the plurality of areas; measuring shapes of the resistpatterns at the plurality of areas by means of a scatterometorytechnique; etching the etching target layer by use of the resist filmwith the resist patterns formed thereon as an etching mask, and removingthe resist film from the substrate, thereby forming etched patterns atthe plurality of areas; measuring shapes of the etched patterns at theplurality of areas by means of a scatterometory technique; anddetermining a management span of combinations of a light exposure amountand a focus value admissible to obtain an etched pattern with apredetermined shape, with reference to the combinations of a lightexposure amount and a focus value used in the sequential light exposurefor the plurality of areas, measurement results of the shapes of theresist patterns formed at the plurality of areas, and measurementresults of the shapes of the etched patterns formed at the plurality ofareas.

In the third aspect described above, the method may further comprise:determining one combination of a light exposure amount and a focus valuewithin the management span after determining the management span;forming a resist film on an etching target layer disposed on a productsubstrate, and performing light exposure with a predetermined productpattern on the resist film, while using the combination of a lightexposure amount and a focus value thus determined, along with subsequentdevelopment; and etching the etching target layer and removing theresist film, thereby forming an etched pattern; measuring a shape of theetched pattern by means of a scatterometory technique; judging whetheror not the shape of the etched pattern is within a predeterminedadmissible dimension range; and, if the shape of the etched pattern isout of the admissible dimension range, determining a new combination ofa light exposure amount and a focus value within the management spansuch that a shape of an etched pattern to be formed on another productsubstrate subsequently processed is brought into the admissibledimension range.

In the third aspect described above, the method may further comprise:determining one combination of a light exposure amount and a focus valuewithin the management span after determining the management span;forming a resist film on an etching target layer disposed on a productsubstrate, and performing light exposure with a predetermined productpattern on the resist film, while using the combination of a lightexposure amount and a focus value thus determined, along with subsequentdevelopment; and etching the etching target layer and removing theresist film, thereby forming an etched pattern; measuring a shape of theetched pattern by means of a scatterometory technique; judging whetheror not the shape of the etched pattern is within a predeterminedadmissible dimension range; if the shape of the etched pattern formed onthe product substrate is out of the predetermined admissible dimensionrange, and a new combination of a light exposure amount and a focusvalue, determined such that a shape of an etched pattern to be formed onanother product substrate subsequently processed is brought into theadmissible dimension range, is out of the management span, performinglight exposure with the product pattern on said another productsubstrate, while using the new combination of a light exposure amountand a focus value thus determined, along with subsequent development;and measuring a shape of a resist pattern thereby obtained; if the shapeof the resist pattern is within a predetermined dimension range,determining a new management span of combinations of a light exposureamount and a focus value, with reference to a target dimension of thetest pattern, the shapes of the resist patterns formed on the testsubstrate, and the combinations of a light exposure amount and a focusvalue used in the sequential light exposure; and, if the shape of theresist pattern is out of a predetermined dimension range, re-executing aseries of processes to determine a new management span of combinationsof a light exposure amount and a focus value, while using a new testsubstrate.

According to a fourth aspect of the present invention, there is provideda light exposure condition setting method comprising: forming a resistfilm on an etching target layer disposed on a test substrate, andperforming sequential light exposure with a predetermined test patternon the resist film sequentially at a plurality of areas, whilerespectively using different combinations of a light exposure amount anda focus value, along with subsequent development, thereby forming resistpatterns at the plurality of areas; measuring shapes of the resistpatterns at the plurality of areas by means of a scatterometorytechnique; forming a resist film on an etching target layer disposed ona product substrate, and performing light exposure with a predeterminedproduct pattern on the resist film, while using a predeterminedcombination of a light exposure amount and a focus value, along withsubsequent development, etching, and resist film removal, therebyforming an etched patterns; and measuring shapes of the etched patternsby means of a scatterometory technique; and, if the etched patternsinclude an etched pattern at an area with a shape out of an admissibledimension range, changing the combination of a light exposure amount anda focus value used for performing light exposure on a product substrate,such that shapes of all etched patterns are brought into the admissibledimension range, with reference to the combinations of a light exposureamount and a focus value used in the sequential light exposure for theplurality of areas on the test substrate and measurement data of theshapes of the resist patterns formed on the test substrate.

In the fourth aspect described above, the method may be arranged suchthat a new combination of a light exposure amount and a focus value isapplied to an area with a shape of an etched pattern out of theadmissible dimension range, and a preceding combination of a lightexposure amount and a focus value is applied to an area with a shape ofan etched pattern within the admissible dimension range.

According to a fifth aspect of the present invention, there is provideda substrate processing apparatus comprising: a light exposure processingsection configured to perform light exposure with a predeterminedpattern on a resist film formed on an etching target layer disposed on asubstrate; a pattern shape measuring section configured to measure ashape of a resist pattern and a shape of an etched pattern by means of ascatterometory technique; and a control section configured to controlthe light exposure processing section and the pattern shape measuringsection, wherein the control section makes reference to: a result ofperforming sequential light exposure with a predetermined test patternon a resist film formed on a test substrate, sequentially at a pluralityof areas, while respectively using different combinations of a lightexposure amount and a focus value, along with subsequent development,thereby forming resist patterns at the plurality of areas, and thenmeasuring shapes of the resist patterns at the plurality of areas by thepattern shape measuring section; the combinations of a light exposureamount and a focus value used in the sequential light exposure for theplurality of areas; and a result of performing light exposure with apredetermined product pattern on a resist film formed on an etchingtarget layer disposed on a product substrate, while using apredetermined combination of a light exposure amount and a focus value,along with subsequent development, etching, and resist film removal,thereby forming an etched patterns; and measuring shapes of the etchedpatterns by the pattern shape measuring section, if the etched patternsinclude an etched pattern at an area with a shape out of an admissibledimension range, and when the control section changes the combination ofa light exposure amount and a focus value used for performing lightexposure on a product substrate, such that shapes of all etched patternsare brought into the admissible dimension range.

In the fifth aspect described above, the control section may be arrangedsuch that a new combination of a light exposure amount and a focus valueis applied to an area with a shape of an etched pattern out of theadmissible dimension range, and a preceding combination of a lightexposure amount and a focus value is applied to an area with a shape ofan etched pattern within the admissible dimension range.

According to a sixth aspect of the present invention, there is provideda computer program including software for execution on a computer, usedfor a substrate processing apparatus, which comprises a light exposureprocessing section configured to perform light exposure with apredetermined pattern on a resist film formed on a substrate, and apattern shape measuring section configured to measure a shape of aresist pattern and a shape of an etched pattern by means of ascatterometory technique, wherein the software, when executed by thecomputer, controls the apparatus to perform a method comprising: forminga resist film on an etching target layer disposed on a test substrate,and performing sequential light exposure with a predetermined testpattern on the resist film sequentially at a plurality of areas, whilerespectively using different combinations of a light exposure amount anda focus value, along with subsequent development, thereby forming resistpatterns at the plurality of areas; measuring shapes of the resistpatterns at the plurality of areas by means of a scatterometorytechnique; forming a resist film on an etching target layer disposed ona product substrate, and performing light exposure with a predeterminedproduct pattern on the resist film, while using a predeterminedcombination of a light exposure amount and a focus value, along withsubsequent development, etching, and resist film removal, therebyforming an etched patterns; and measuring shapes of the etched patternsby means of a scatterometory technique; and, if the etched patternsinclude an etched pattern at an area with a shape out of an admissibledimension range, changing the combination of a light exposure amount anda focus value used for performing light exposure on a product substrate,such that shapes of all etched patterns are brought into the admissibledimension range, with reference to the combinations of a light exposureamount and a focus value used in the sequential light exposure for theplurality of areas on the test substrate and measurement data of theshapes of the resist patterns formed on the test substrate.

In the sixth aspect described above, the computer program may bearranged such that a new combination of a light exposure amount and afocus value is applied to an area with a shape of an etched pattern outof the admissible dimension range, and a preceding combination of alight exposure amount and a focus value is applied to an area with ashape of an etched pattern within the admissible dimension range.

According to the present invention, a resist film formed on an etchingtarget layer disposed on a test substrate is subjected to sequentiallight exposure using different combinations of a light exposure amountand a focus value respectively at a plurality of areas, along withsubsequent development, and the shapes of resist patterns thereby formedare measured by means of a scatterometory technique. Then, the etchingtarget layer is etched at the plurality of areas, and the shapes ofetched patterns thereby formed are measured by means of a scatterometorytechnique. Then, a management span of combinations of a light exposureamount and a focus value admissible to obtain an etched pattern with apredetermined shape is determined with reference to the data describedabove. Consequently, it is possible to easily obtain an etched patternwithin an admissible dimension range, thereby suppressing generation ofdefective products in the etching process.

Further, according to the present invention, a resist film formed on anetching target layer disposed on a test substrate is subjected tosequential light exposure using different combinations of a lightexposure amount and a focus value respectively at a plurality of areas,along with subsequent development, and the shapes of resist patternsthereby formed are measured by means of a scatterometory technique.Then, a resist film formed on an etching target layer disposed on aproduct substrate is subjected to patterning with a predeterminedproduct pattern, and the shapes of etched patterns thereby formed aremeasured by means of a scatterometory technique. Then, the combinationof a light exposure amount and a focus value used for performing lightexposure on a product substrate is changed with reference to the datadescribed above, such that the shapes of all etched patterns are broughtinto an admissible dimension range. Consequently, it is possible tosuppress planar fluctuations in the shapes of etched patterns on asubstrate, and easily obtain etched patterns within the admissibledimension range all over the substrate, thereby suppressing generationof defective products.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] This is a view showing the arrangement of a wafer processingsystem.

[FIG. 2] This is a view schematically showing the arrangement of anintegrated computer.

[FIG. 3] This is a flowchart showing a method for conditioning the waferprocessing system.

[FIG. 4] This is a view showing a matrix used for sequential lightexposure.

[FIG. 5] This is a graph showing the relationship of the line widths ofresist patterns obtained by sequential light exposure, relative to thelight exposure amount and focus value.

[FIG. 6] This is a graph showing the relationship of the line widths ofetched patterns, relative to the light exposure amount and focus value.

[FIG. 7A] This is a view showing an example of the relationship betweenthe cross-sectional shape of a resist pattern and the cross-sectionalshape of an etched pattern.

[FIG. 7B] This is a view showing an example of the relationship betweenthe cross-sectional shape of a resist pattern and the cross-sectionalshape of an etched pattern.

[FIG. 7C] This is a view showing an example of the relationship betweenthe cross-sectional shape of a resist pattern and the cross-sectionalshape of an etched pattern.

[FIG. 7D] This is a view showing an example of the relationship betweenthe cross-sectional shape of a resist pattern and the cross-sectionalshape of an etched pattern.

[FIG. 8] This is a flowchart showing a method for changing combinationsof a light exposure amount and a focus value.

[FIG. 9] This is a view showing the relationship of a matrix used forsequential light exposure, relative to a management span of combinationsof a light exposure amount and a focus value.

[FIG. 10] This is a flowchart showing a method for conditioning thewafer processing system to decrease generation of planar fluctuations ofetched patterns.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will now be described withreference to the accompanying drawings. The following explanation willbe exemplified by a wafer processing system in which an etching targetfilm (etching target layer) formed on a semiconductor wafer W is etchedby use of a resist pattern to form an etched pattern.

FIG. 1 is a view showing the arrangement of a wafer processing systemfor patterning an etching target film. This wafer processing systemincludes a resist coating/developing apparatus 12, a light exposureapparatus 13, an etching apparatus 14, a resist removing apparatus 15, afirst line width measuring unit (ODP-1) 16 for measuring the shape of aresist pattern, a second line width measuring unit (ODP-2) 17 formeasuring the shape of an etched pattern, and an integrated computer 11.

The resist coating/developing apparatus 12 is arranged to form a resistfilm on an etching target film, such as an inter-level insulating film,and to develop the resist film treated by a light exposure process. Theetching target film has been formed by a CVD method or SOD (spin ondielectric) method in a film formation apparatus (not shown).

The light exposure apparatus 13 is arranged to perform light exposure ona resist film by use of a predetermined mask pattern (photo-mask) underpredetermined light exposure conditions.

The etching apparatus 14 is arranged to etch an etching target film byuse of a resist pattern as an etching mask. The etching apparatus 14 isformed of, e.g., a plasma etching apparatus.

The resist removing apparatus 15 is arranged to remove a resist patternfrom a wafer W treated by an etching process. The resist removingapparatus 15 is formed of, e.g., a plasma ashing apparatus.

The first line width measuring unit (ODP-1) 16 is arranged to utilizescatterometory technique to measure the shape of a resist pattern formedby a development process in the resist coating/developing apparatus 12.

The second line width measuring unit (ODP-2) 17 is arranged to utilize ascatterometory technique to measure the shape of an etched pattern of anetching target film formed by an etching process in the etchingapparatus 14. The second line width measuring unit (ODP-2) 17 has thesame structure as the first line width measuring unit (ODP-1) 16, anddiffers therefrom only in the measurement target.

The scatterometory technique is disclosed in, e.g., Jpn. Pat. Appln.KOKAI Publication No. 2002-260994, and is arranged, as follows.Specifically, a diffraction light intensity distribution concerning aplurality of pattern shapes is calculated to fabricate, e.g., a libraryin advance. Then, light is radiated onto a measurement target pattern,and the angular direction distribution of diffraction light intensity isdetected. Then, the detection result is compared with the librarydescribed above, thereby estimating the width, height, and so forth ofthe measurement target pattern by means of pattern matching.

In this embodiment, the integrated computer 11 is arranged to controlthe first and second line width measuring units 16 and 17 and lightexposure apparatus 13. The integrated computer 11 may be arranged tocontrol the resist coating/developing apparatus 12, etching apparatus14, and resist removing apparatus 15 in addition to the units 16 and 17and apparatus 13, and may be arranged to further control a filmformation apparatus (not shown).

FIG. 2 is a view schematically showing the arrangement of the integratedcomputer 11. The integrated computer 11 includes a process controller(CPU) 31, a data I/O (input/output) section 32, and a storage section 33that stores various kinds of data and programs. The data I/O section 32includes, e.g., a keyboard and a display, wherein the keyboard is usedfor a process operator to input commands for determining a managementspan for a light exposure process, as described later, and the displayis used for showing visualized images of calculation results obtained bythe process controller (CPU) 31. The integrated computer 11 furtherincludes interfaces (IF) 34 a, 34 b, and 34 c that allow datacommunication to and from the first line width measuring unit (ODP-1)16, second line width measuring unit (DOP-2) 17, and light exposureapparatus 13, respectively.

More specifically, the storage section 33 stores a light exposuremanagement program 36, a first analysis program 37 a, a first library(data base) 37 b, a second analysis program 38 a, and a second library(data base) 38 b. The light exposure management program 36 is used forthe process controller (CPU) 31 to determine a light exposure managementspan and to change combinations of a light exposure amount and a focusvalue, as described later. The first analysis program 37 a is used foranalyzing spectro-reflectometry spectra measured by the first line widthmeasuring unit (ODP-1) 16, while the first library (data base) 37 b isused for this analysis. The second analysis program 38 a is used foranalyzing spectro-reflectometry spectra measured by the second linewidth measuring unit (ODP-2) 17, while the second library (data base) 38b is used for this analysis.

The first library 37 b contains units of data concerning parametersshowing the shape of each resist pattern, such as the line width (e.g.,“_(R)CD₁” shown in FIG. 2), bottom width, film thickness, and sidesurface angle, as well as spectro-reflectometry spectra corresponding tothese parameters. Similarly, the second library 38 b contains units ofdata concerning the shape of each etched pattern, such as the line width(e.g., “_(E)CD₁” shown in FIG. 2) and film thickness, as well asspectro-reflectometry spectra corresponding to them. It should be notedthat “line width” denotes the width of the top surface of a pattern, and“bottom width” denotes the width of the bottom of the pattern.

The wafer processing system shown in FIGS. 1 and 2 have two line widthmeasuring units, but may have only one line width measuring unit, whichis used for measuring both of the shapes of the resist pattern andetched pattern. In the latter case, the integrated computer 11 may needto know whether a measurement target is the resist pattern or etchedpattern. For example, it may be arranged such that, after the type of ameasurement target is input by an operator into the integrated computer11 through the data I/O section 32, the line width measuring unit startsmeasurement. Alternatively, the integrated computer 11 may store thetransfer history of wafers so that the integrated computer 11 canautomatically know the state of a wafer, such that it has been processedin the resist coating/developing apparatus 12 or it has been processedin the resist removing apparatus 15.

Next, an explanation will be given of a method for conditioning thewafer processing system to form an etched pattern with a predeterminedshape in the wafer processing system, with reference to the flowchartshown in FIG. 3. This method for conditioning the wafer processingsystem is virtually a method for adjusting the exposure amount and focusvalue of the light exposure apparatus 13.

At first, an etching target film, such as a low-k film, is formed on awafer W to prepare a test wafer W in a film formation apparatus (notshown) (Step 1). Then, the wafer W is transferred into the resistcoating/developing apparatus 12, in which a resist film is formed on theetching target film (Step 2). The wafer W with a resist film formedthereon is transferred into the light exposure apparatus 13, in whichthe following light exposure process is performed (Step 3).Specifically, as shown in FIG. 4, a matrix is formed while the lightexposure amount is sequentially changed at regular intervals within arange of from E₀ to E_(n) (n is natural number), and the focus value issequentially changed at regular intervals within a range of from F₀ toF_(m) (m is natural number). Then, the light exposure process isperformed such that each of the matrix elements (E_(i),F_(j)) isprocessed by one shot, (which will be referred to as “reference lightexposure”, hereinafter). This Step 3 is performed by use of a photo-maskthat provides a resist pattern with a line width H0 (which will bereferred to as “test pattern”) where the light exposure amount and focusvalue are appropriate. Further, the target value of the line width of anetched pattern to be formed is also set at H0.

Then, the wafer W processed by the reference light exposure is returnedinto the resist coating/developing apparatus 12, in which a developmentprocess is performed (Step 4). Consequently, predetermined resistpatterns are formed.

The wafer W with the resist patterns formed thereon is transferred intothe first line width measuring unit (ODP-1) 16, in which the patternshapes of the resist patterns are measured by means of a scatterometorytechnique (Step 5). In this Step 5, for every light exposure shot, i.e.,for every matrix element (E_(i),F_(j)), light having a predeterminedwavelength is radiated onto, e.g., the center of the matrix element, andspectro-reflectometry spectra obtained at this time are measured.

Then, in the integrated computer 11, waveforms measured by the processof Step 5 are checked with reference to data concerning resist patternsrecorded in the first library 37 b to obtain the line widths of theresist patterns. Further, this result is matched and linked with thecombinations of a light exposure amount and a focus value used in Step 3(Step 6). Where a scatterometory technique is used for the shape of aresist pattern, not only the line width, but also the bottom width andside surface inclination can be obtained. However, the line width isused for representing the shape of a resist pattern, hereinafter.

FIG. 5 is a graph showing an example of the relationship of the linewidths of the resist patterns obtained by Step 6, relative to the lightexposure amount and focus value. This graph can be used as a material toconfirm the degree of misalignment generated between the line width of aresist pattern and the line width of an etched pattern to be formed.Further, this graph can be used as a reference data when the combinationof a light exposure amount and a focus value needs to be changed toobtain an etched pattern with a predetermined shape, in the course ofprocessing product wafers W over time after a management span has beendetermined, as described later.

Then, the wafer W is transferred from the first line width measuringunit (ODP-1) 16 into the etching apparatus 14, in which the etchingtarget film is etched by use of the resist patterns as an etching mask(Step 7). For example, the etching conditions of a plasma etchingprocess can be changed by adjusting the vacuum level inside a chamberthat accommodates a wafer W, the flow rate of a gas supplied into thechamber, the voltage for plasma generation, the process time. However,since such adjustment is not easy, the etching conditions are fixed atconditions for manufacturing products, in general. Accordingly, Step 7is performed under such fixed conditions.

The wafer W treated by the etching process is transferred into theresist removing apparatus 15, in which a resist removing process isperformed (Step 8). Consequently, etched patterns appear on the surfaceof the wafer W. Then, the wafer W is transferred into the second linewidth measuring unit (ODP-2) 17, in which the shapes of the etchedpatterns are measured by means of a scatterometory technique (Step 9).In the Step 9, for every light exposure shot, light is radiated onto thecenter of the matrix element, and spectro-reflectometry spectra obtainedat this time are measured, as in Step 5 descried above.

Then, in the integrated computer 11, waveforms measured by the processof Step 9 are checked with reference to data concerning etched patternsrecorded in the second library 38 b to obtain the line widths of theetched patterns. Further, this result is linked with the combinations ofa light exposure amount and a focus value respectively used for thematrix elements (E_(i),F_(j)) (Step 10).

FIG. 6 is a graph showing an example of the relationship of the linewidths of the etched patterns obtained by Step 10, relative to the lightexposure parameters (i.e., the light exposure amount and focus value).As can be seen by comparison between FIGS. 5 and 6, a line representinga light exposure amount E_(i) is closest to the line width H0 in FIG. 5,while a line representing a light exposure amount E_(i+1) is closest tothe line width H0 in FIG. 6. Accordingly, a combination of a lightexposure amount and a focus value optimum to forming a resist patternwith high accuracy in shape is different from a combination of a lightexposure amount and a focus value optimum to forming an etched patternwith high accuracy in shape.

The reason of this difference being generated will be briefly explainedwith reference to FIGS. 7A to 7D. FIGS. 7A to 7D are views showing anexample of the relationship between the cross-sectional shape of aresist pattern and the cross-sectional shape of an etched pattern.

As shown in FIG. 7A, where a resist pattern 61 a is rectangular and hasgood resistance to an etching atmosphere, an etched pattern 62 a isformed to have a line width W equal to the line width H of the resistpattern 61 a. On the other hand, as shown in FIG. 7B, where a resistpattern 61 b is rectangular and has poor resistance to an etchingatmosphere, an etched pattern 62 b is formed to have a line width Wsmaller than the original line width H of the resist pattern 61 b,because the resist pattern 61 b is eroded during the etching process.Further, as shown in FIG. 7C, where a resist pattern 61 c istrapezoidal, an etched pattern 62 c is formed to have a line width Wlarger than the line width H of the resist pattern 61 c. In reverse, asshown in FIG. 7D, where a resist pattern 61 d is inverted-trapezoidal,an etched pattern 62 d is formed to have a line width W smaller than theline width H of the resist pattern 61 d.

As described above, the line width of an etched pattern is greatlyinfluenced by the shape of a resist pattern. Further, it is difficult toobtain a good etched pattern without suitably performing light exposureon a resist film. Accordingly, it is beneficial to measure the shapes ofresist patterns and link it with light exposure parameters to fabricatedata thereon, as in Steps 5 and 6, in order to bring the line widths ofetched patterns into an admissible dimension range, as well.

After data concerning the line widths of etched patterns is obtained inStep 10, a span of combinations of a light exposure amount and a focusvalue necessary for obtaining an etched pattern with a predeterminedshape (which will be referred to as “management span”, hereinafter) isdetermined in the integrated computer 11 (Step 11).

This Step 11 is performed, as follows.

At first, since a target line width of an etched pattern has a certainadmissible margin, this margin can be defined as δ0. According to thisdefinition, it is admissible if the line width of the etched pattern iswithin a range of H0±δ0. This admissible range of the etched pattern isshown in FIG. 6 as a shaded region. This region corresponds to themanagement span.

A management span is thus formed on combinations of a light exposureamount and a focus value, and a combination of a light exposure amountand a focus value to be applied to an actual light exposure process isdetermined within this management span. With this arrangement, an etchedpattern can be easily obtained within an admissible dimension range.Consequently, it is possible to decrease the number of defectiveproducts formed by the etching process.

In the example described above, a management span of combinations of alight exposure amount and a focus value is determined with referenceonly to the line widths of etched patterns. However, as describedpreviously, where a scatterometory technique is used, not only the linewidth of an etched pattern, but also the bottom width and inclinationcan be obtained. Accordingly, a management span may be obtained by thefollowing method. Specifically, at first, as described above, an initialmanagement span is obtained with reference to the line widths of etchedpatterns. Then, the management span is narrowed with reference to thebottom widths. Then, the management span is further narrowed withreference to the pattern inclination values, thereby obtaining a finalmanagement span of combinations of a light exposure amount and a focusvalue.

Further, in the example described above, a management span ofcombinations of a light exposure amount and a focus value is determinedby use of one test wafer W. Alternatively, two test wafers W may be usedsuch that one of them is processed by Steps 1 to 5 and is then stored,while the other is processed by Steps 1 to 4 and Steps 7 to 11 (i.e.,the shapes of resist patterns are not measured) and is then stored. Inthis case, the two test wafers W can be considered to have substantiallythe same shapes of resist patterns formed thereon. Where the test wafersW are stored, as described above, they can be used as references whenre-conditioning of the wafer processing system is required.

Step 1 to 11 described above are performed before a process of productwafers is started. When a process of product wafers is actuallyperformed after Step 11, the line width of a resist pattern may go outof an admissible dimension range, due to changes with time in theenvironment for manufacturing product wafers. These changes are causedby cleaning of the etching chamber, fluctuations in the nature of theetching target film, fluctuations in the nature of the resist film, amaintenance operation of the light exposure apparatus and resistcoating/developing apparatus, and so forth. In order to solve thisproblem, adjustment of the light exposure amount and focus value may berequired. A conditioning method performed for this purpose will beexplained with reference to the flowchart shown in FIG. 8.

After a management span of combinations of a light exposure amount and afocus value is determined by Step 11, a combination of conditions, i.e.,a light exposure amount and a focus value, optimum to obtaining anetched pattern with a predetermined line width, is determined withinthis management span (Step 12). FIG. 9 shows a view in which amanagement span obtained by Step 11 is combined with the matrix shown inFIG. 4. In FIG. 9, a shaded region corresponds to the management span.For example, in Step 12, a combination of a light exposure amount and afocus value located essentially at the center of this management spanmay be used as initial set values for performing light exposure onproduct wafers W.

After a light exposure amount and a focus value are determined, asdescribed above, a product wafer W with an etching target film formedthereon is prepared (Step 13), and a resist film is formed on theetching target film (Step 14). Then, the resist film is subjected tolight exposure with a predetermined product pattern at the lightexposure amount and focus value determined as described above, and thento development (Step 16). Then, while the resist patterns thus formedare used as an etching mask, the etching target film is etched to formetched patterns (Step 17). Then, the resist patterns are removed (Step18). For every lot of product wafers W with etched patterns thus formedthereon or for a predetermined number of such product wafers W, the linewidths of the formed etched patterns are measured by the second linewidth measuring unit (ODP-2) 17 (Step 19).

The line width of an etched pattern formed on product wafers W has on anadmissible dimension range, as a matter of course. Accordingly, it isthen judged whether or not the measured line widths are within anadmissible range (Step 20). Where the line widths are within theadmissible range, the flow returns to Step 13, and the process ofproduct wafers W is continued. Where a line width is out of theadmissible dimension range, the light exposure amount and focus valueneed to be changed by the integrated computer 11, so that the linewidths of etched patterns to be formed on product wafers W are broughtinto the admissible dimension range.

For example, where the line width of an etched pattern is larger thanthe value of the admissible dimension range, it is estimated that thecharacteristic lines shown in FIG. 6 are shifted upward, in the case ofdata shown in FIG. 6, for example. In this case, by adjusting, e.g., thelight exposure amount from the initial value E_(i+1) to E_(i) orE_(i)−1, or further to a lower value, the line width of the etchedpattern can be brought into the admissible dimension range.

However, a combination of a light exposure amount and a focus value thusadjusted may be out of the management span obtained by Step 11. Thiscombination is undesirable in light of the quality guarantee of productwafers W, because the light exposure process is unlikely to be suitablyperformed.

Accordingly, where a line width measured in Step 19 is out of theadmissible dimension range, it is judged whether or not the line widthof the etched pattern can be brought into the admissible dimension rangeby changing the combination of a light exposure amount and a focus valuewithin the management span obtained by Step 11 (Step 21).

Where the line width of the etched pattern can be brought into theadmissible dimension range by changing the combination of a lightexposure amount and a focus value within the management span, thecombination of a light exposure amount and a focus value isautomatically changed to this combination by the integrated computer 11(Step 22). This method is mainly applied to a case where the number ofchanging operations ever performed is still small, such as a case wherethe combination of a light exposure amount and a focus value is changedfor the first time from the start of the process of product wafers W. Itmay be arranged such that the combination of a light exposure amount anda focus value can be manually changed by an operator (a new combinationof a light exposure amount and a focus value is determined by the dataI/O section 32).

After a new combination of a light exposure amount and a focus value isdetermined as described above, the light exposure process is performedby use of the new light exposure amount and focus value on a productwafer W subsequently processed in the light exposure apparatus 13, inaccordance with an instruction from the integrated computer 11 (Step23). Then, development, etching, and resist film removal are performed,and the line widths of etched patterns thereby formed on the productwafer W are measured (Step 24). Then, it is judged whether or not theline widths are within the admissible range (Step 25). Where the linewidths thus measured are within the admissible dimension range, the flowreturns to Step 13, and the process of product wafers W is continued.Where a line width thus measured is out of the admissible dimensionrange, the operation of the light exposure apparatus 13 is stopped andan alarm is raised both by the integrated computer 11 (Step 26). Wherean alarm is raised, an examination of the etched patterns on the productwafer W and a check of the wafer processing system are performed by anoperator, so that product wafers W can be processed.

On the other hand, as a result of judgment in Step 21, where the linewidth of an etched pattern cannot be brought into the admissibledimension range by changing the combination of a light exposure amountand a focus value within the management span, the light exposureapparatus 13 is once adjusted to use a new combination of a lightexposure amount and a focus value outside the management span (Step 27).

Next, an explanation will be given as to why there is such a case wherethe line width of an etched pattern cannot be brought into an admissibledimension range by changing the combination of a light exposure amountand a focus value within the management span.

Specifically, as described above, where the line width of an etchedpattern can be brought into the admissible dimension range by changingthe combination of a light exposure amount and a focus value within themanagement span, the light exposure amount and focus value are adjustedin Step 22. With such adjustment, for example, the combination of alight exposure amount and a focus value is shifted from the center ofthe shaded region first set in FIG. 9 to an outer position within theshaded region. Where such a change is repeated several times, a newcombination of a light exposure amount and a focus value may go out ofthe management span.

In this case, in Step 27, the light exposure apparatus 13 is onceadjusted to use a new combination of a light exposure amount and a focusvalue outside the management span, so that the productivity rate isprevented from being deteriorated due to stoppage of the waferprocessing system. This is so, because product wafers W may besufficiently processed by use of a new combination of a light exposureamount and a focus value thus set.

After the light exposure apparatus 13 is adjusted to use the new lightexposure amount and focus value thus set, the light exposure with theproduct pattern is performed under the new conditions on another productwafer W. Then, development is performed, and the shapes (line widths) ofresist patterns thereby formed are checked (Step 28).

The line width of a resist pattern is required to be within a certainadmissible dimension range, so that the line width of an etched patternto be formed thereafter is brought into an admissible dimension range.Accordingly, it is judged whether or not the line widths of the resistpatterns obtained by Step 28 are within the admissible dimension range(Step 29). Where they are within the admissible range, a new managementspan of combinations of a light exposure amount and a focus value isdetermined and reset, with reference to the shapes of resist patternsformed on the test substrate in advance, the target dimension of thetest pattern, and the combinations of a light exposure amount and afocus value used in the reference light exposure (Step 30). Then, aftera new combination of a light exposure amount and a focus value isdetermined, the flow returns to Step 13, and the process of productwafers W is continued.

On the other hand, where the line width of a resist pattern is out ofthe certain dimension range, the process of product wafers W is stopped.Then, by use of a new test substrate, the processes of from Step 1 toStep 11 are performed again, so that a new management span ofcombinations of a light exposure amount and a focus value is determined(Step 31). Thereafter, the process of from Step 12 can be restarted.

Where this process of Step 31 is performed, it is preferable to check inadvance the apparatuses used for sequential processes from the etchingtarget film formation through the resist film formation and the etchingprocess to the resist film removal. In this case, the time period to thenext check of the system can be prolonged, while fluctuations of processconditions during this time period is suppressed, so the quality ofproduct wafers W can be easily maintained at a certain level.

Next, an explanation will be given of a method for adjusting the lightexposure apparatus 13, where products are manufactured in the waferprocessing system, with reference to the flowchart shown in FIG. 10.This method is intended to suppress planar fluctuations of the shapesobtained by an etching process on a wafer W, so as to obtain etchedpatterns with a predetermined shape for all the shots on the surface ofthe wafer W.

At first, a test wafer is processed by use of the same operations asSteps 1 to 6 shown in FIG. 3 described above. Specifically, an etchingtarget film is formed (Step 101), and a resist film is formed (Step102). Then, reference light exposure is performed thereon by use of aphoto-mask having a test pattern (Step 103), and is followed by adevelopment process (Step 104). Then, the shapes of resist patternsthereby formed are measured by means of a scatterometory technique (Step105). Then, the combinations of a light exposure amount and a focusvalue used in the reference light exposure are linked with dataconcerning the shapes of the resist patterns (Step 106).

Subsequently, a product wafer W with an etching target film formedthereon is prepared (Step 107), and a resist film is formed (Step 108).Then, light exposure is performed thereon by use of a photo-mask havinga pattern for manufacturing products, along with a combination of alight exposure amount and a focus value empirically known as providingno defective products (Step 109), and is followed by a developmentprocess (Step 110). Then, resist patterns thereby formed are used as anetching mask to perform etching (Step 111), and are then removed by aremoving process (Step 112). Then, the shapes of etched patterns therebyformed are measured by means of a scatterometory technique (Step 113).

Then, it is judged whether or not the line widths of the etched patternsmeasured by Step 113 are within an admissible range all over the surfaceof the product wafer W (Step 114). Where the line widths are within theadmissible range all over the surface of the product wafer W, the flowreturns to Step 107, and the process of product wafers W is continued.

In this respect, there may be a case where the line width of an etchedpattern measured by Step 113 is within the admissible range on a part ofthe product wafer W while the line width of an etched pattern is out ofthe admissible range on another part of the product wafer W. Forexample, it is empirically known that plasma etching processes tend toresult in line widths smaller at the central portion of a wafer W thanat the peripheral portion. In other words, the line widths of etchedpatterns render a doughnut-like distribution. Accordingly, there is acase where the line widths are within the admissible range only on apart of the surface, e.g., the line width of an etched pattern is withinthe admissible range at the central portion of the product wafer W whilethe line width of an etched pattern is out of the admissible range atthe peripheral portion. In this case, according to a first method, thelight exposure amount and focus value are adjusted at the peripheralportion of the product wafer W (Step 115). Further, according to asecond method, the light exposure amount and focus value are adjustedall over the product wafer W (Step 116). However, the second method isusable on the condition that, where the light exposure amount and focusvalue are adjusted all over the product wafer W in accordance withadjustment in the light exposure amount and focus value at theperipheral portion of the product wafer W, the line width still stayswithin the admissible range at the central portion of the product waferW. By use of either one of the methods described above, the line widthsof the etched patterns are brought into the admissible range all overthe product wafer W.

In order to perform such adjustment in the light exposure amount andfocus value, the examination result of the test wafer W described aboveis utilized. For example, in the state described above, the line widthof an etched pattern is within the admissible range at the centralportion of the product wafer W while the line width of an etched patternis out of the admissible range at the peripheral portion. In this case,since the line width is larger than a predetermined line width at theperipheral portion of the product wafer W, the first method is applied,as follows. Specifically, the test wafer W includes an area processed bylight exposure with the same light exposure amount and focus value asthe preceding light exposure amount and focus value used for the productwafer W. At first, a search is made for this light exposure area (shot)to select a light exposure amount and a focus value that provide a linewidth smaller than the line width of the resist pattern of this area.Then, when the light exposure is performed on a product wafer W, thepreceding light exposure amount and focus value are used for the lightexposure at the central portion of the product wafer W, while the newlight exposure amount and focus value are used for the light exposure atthe peripheral portion. Consequently, the line widths of the resistpatterns can be brought into the admissible range all over the productwafer W.

In this first method, the light exposure amount and focus value may beadjusted for every light exposure shot. In this case, the planaruniformity in the line widths of the etched patterns can be moreimproved all over the product wafer W.

On the other hand, where the second method is applied, the followingoperations are used. Specifically, as described above, the test wafer Wincludes an area processed by light exposure with the same lightexposure amount and focus value as the preceding light exposure amountand focus value used for the product wafer W. At first, a search is madefor this light exposure area (shot) to select a combination of a lightexposure amount and a focus value that provide a line width smaller thanthe line width of the resist pattern of this area. In this case, thecombination of a light exposure amount and a focus value selected atthis time is further conditioned such that, where the combination isused for the light exposure at the central portion of the product waferW, the line width of an etched pattern thereby obtained still stayswithin the admissible range. Then, when light exposure is performed on aproduct wafer W, only the new light exposure amount and focus value thusselected are used for the light exposure of the product wafer W. Alsowith this method, the line widths of the resist patterns can be broughtinto the admissible range all over the product wafer W. This secondmethod is mainly applied to a case where the difference in the linewidths of the resist patterns is small between light exposure shots.

In either of the first and second methods, adjustment of the lightexposure amount and focus value is performed in accordance with anoperator's judgment and/or coefficient models designed by operators orengineers.

The embodiment described above is intended only to clarify the technicalcontent of the present invention, and, therefore, the present inventionshould not be construed as being limited to the embodiment. Variousmodifications may be made without departing from the spirit of thepresent invention or the scope of the appended claims.

For example, in place of a single etching apparatus, a plurality ofetching apparatuses may be used, or an etching apparatus including aplurality of etching chambers may be used. Similarly, in place of asingle resist coating/developing apparatus, a plurality of resistcoating/developing apparatuses may be used, or a plurality of resistcoating units and a plurality of development units may be used. In thiscase, individual differences may be present between etching apparatusesor etching chambers, or between resist coating/developing apparatuses,resist coating units, or development units, and bring about fluctuationsof process conditions undetectable under operational conditions normallyset in the apparatuses. In this case, it is preferable to provide allthe processing portions with respective IDs, and to arrange theintegrated computer as follows. Specifically, management spanscorresponding to photolithography process conditions are respectivelyset for combinations of all the IDs, and the combination of a lightexposure amount and a focus value can be changed for every managementspan to obtain an etched pattern with a predetermined shape.

Further, where data concerning such changes are accumulated andutilized, it is possible to improve the timing and accuracy of changesin the combination of a light exposure amount and a focus value.

In the embodiment described above, the present invention is applied to asemiconductor wafer. Alternatively, the present invention may be appliedto another substrate, such as glass substrate used for an FPD (flatpanel display device), a representative of which is a liquid crystaldisplay device.

INDUSTRIAL APPLICABILITY

The present invention can be preferably utilized for a case where highaccuracy in line width is required in manufacturing semiconductordevices or FPDs.

1: A light exposure condition setting method comprising: forming aresist film on an etching target layer disposed on a test substrate, andperforming sequential light exposure with a predetermined test patternon the resist film sequentially at a plurality of areas, whilerespectively using different combinations of a light exposure amount anda focus value, along with subsequent development, thereby forming resistpatterns at the plurality of areas; measuring shapes of the resistpatterns at the plurality of areas by means of a scatterometorytechnique; etching the etching target layer by use of the resist filmwith the resist patterns formed thereon as an etching mask, and removingthe resist film from the substrate, thereby forming etched patterns atthe plurality of areas; measuring shapes of the etched patterns at theplurality of areas by means of a scatterometory technique; anddetermining a management span of combinations of a light exposure amountand a focus value admissible to obtain an etched pattern with apredetermined shape, with reference to the combinations of a lightexposure amount and a focus value used in the sequential light exposurefor the plurality of areas, measurement results of the shapes of theresist patterns formed at the plurality of areas, and measurementresults of the shapes of the etched patterns formed at the plurality ofareas. 2: The light exposure condition setting method according to claim1, wherein the method further comprises: determining one combination ofa light exposure amount and a focus value within the management spanafter determining the management span; forming a resist film on anetching target layer disposed on a product substrate, and performinglight exposure with a predetermined product pattern on the resist film,while using the combination of a light exposure amount and a focus valuethus determined, along with subsequent development; and etching theetching target layer and removing the resist film, thereby forming anetched pattern; measuring a shape of the etched pattern by means of ascatterometory technique; judging whether or not the shape of the etchedpattern is within a predetermined admissible dimension range; and, ifthe shape of the etched pattern is out of the admissible dimensionrange, determining a new combination of a light exposure amount and afocus value within the management span such that a shape of an etchedpattern to be formed on another product substrate subsequently processedis brought into the admissible dimension range. 3: The light exposurecondition setting method according to claim 1, wherein the methodfurther comprises: determining one combination of a light exposureamount and a focus value within the management span after determiningthe management span; forming a resist film on an etching target layerdisposed on a product substrate, and performing light exposure with apredetermined product pattern on the resist film, while using thecombination of a light exposure amount and a focus value thusdetermined, along with subsequent development; and etching the etchingtarget layer and removing the resist film, thereby forming an etchedpattern; measuring a shape of the etched pattern by means of ascatterometory technique; judging whether or not the shape of the etchedpattern is within a predetermined admissible dimension range; if theshape of the etched pattern formed on the product substrate is out ofthe predetermined admissible dimension range, and a new combination of alight exposure amount and a focus value, determined such that a shape ofan etched pattern to be formed on another product substrate subsequentlyprocessed is brought into the admissible dimension range, is out of themanagement span, performing light exposure with the product pattern onsaid another product substrate, while using the new combination of alight exposure amount and a focus value thus determined, along withsubsequent development; and measuring a shape of a resist patternthereby obtained; if the shape of the resist pattern is within apredetermined dimension range, determining a new management span ofcombinations of a light exposure amount and a focus value, withreference to a target dimension of the test pattern, the shapes of theresist patterns formed on the test substrate, and the combinations of alight exposure amount and a focus value used in the sequential lightexposure; and, if the shape of the resist pattern is out of apredetermined dimension range, re-executing a series of processes todetermine a new management span of combinations of a light exposureamount and a focus value, while using a new test substrate. 4: The lightexposure condition setting method according to claim 3, wherein, inorder to determine the new management span, while using the new testsubstrate, the method further comprises, prior to processing the newtest substrate, checking apparatuses used for a series of processes fromresist film formation through an etching process to resist film removal.5: The light exposure condition setting method according to claim 1,wherein the plurality of areas form a matrix with a light exposureamount and a focus value used as parameters. 6: The light exposurecondition setting method according to claim 1, wherein a measurementtarget of a pattern includes a line width of the pattern. 7: A substrateprocessing apparatus comprising: a light exposure processing sectionconfigured to perform light exposure with a predetermined pattern on aresist film formed on an etching target layer disposed on a substrate; apattern shape measuring section configured to measure a shape of aresist pattern and a shape of an etched pattern by means of ascatterometory technique; and a control section configured to controlthe light exposure processing section and the pattern shape measuringsection, wherein the control section makes reference to: a result ofperforming sequential light exposure with a predetermined test patternon a resist film formed on a substrate, sequentially at a plurality ofareas, while respectively using different combinations of a lightexposure amount and a focus value, along with subsequent development,thereby forming resist patterns at the plurality of areas, and thenmeasuring shapes of the resist patterns at the plurality of areas by thepattern shape measuring section; a result of etching the etching targetlayer by use of the resist film with the resist patterns formed thereonas an etching mask, thereby forming etched patterns at the plurality ofareas, and then measuring shapes of the etched patterns at the pluralityof areas by the pattern shape measuring section; and the combinations ofa light exposure amount and a focus value used in the sequential lightexposure for the plurality of areas, so as to determine a managementspan of combinations of a light exposure amount and a focus valueadmissible to obtain a predetermined etched pattern. 8: The substrateprocessing apparatus according to claim 7, wherein, if a shape of anetched pattern formed on a product substrate by performing lightexposure thereon, while using one combination of a light exposure amountand a focus value determined within the management span, is out of theadmissible dimension range, the control section determines a newcombination of a light exposure amount and a focus value within themanagement span such that a shape of an etched pattern to be formed onanother product substrate subsequently processed is brought into theadmissible dimension range. 9: The substrate processing apparatusaccording to claim 7, wherein, if a shape of an etched pattern formed ona product substrate by performing light exposure thereon, while usingone combination of a light exposure amount and a focus value determinedwithin the management span, is out of the admissible dimension range,and a new combination of a light exposure amount and a focus value,determined such that a shape of an etched pattern to be formed onanother product substrate subsequently processed is brought into theadmissible dimension range, is out of the management span, the controlsection controls the light exposure processing section to perform lightexposure on said another product substrate, while using the newcombination of a light exposure amount and a focus value thusdetermined, and, if a shape of a resist pattern formed on said anotherproduct substrate by performing light exposure thereon, while using thenew combination of a light exposure amount and a focus value, is withina predetermined dimension range, the control section determines a newmanagement span of combinations of a light exposure amount and a focusvalue, with reference to the shapes of the resist patterns formed on thesubstrate by the sequential light exposure, a target dimension of aphoto mask used for forming the resist patters, and the combinations ofa light exposure amount and a focus value used in the sequential lightexposure. 10: The substrate processing apparatus according to claim 7,wherein the pattern shape measuring section includes a first measuringsection configured to measure a shape of a resist pattern and a secondmeasuring section configured to measure a shape of an etched pattern.11: A computer readable medium containing program instructions forexecution on a processor used for a substrate processing apparatus,which comprises a light exposure processing section configured toperform light exposure with a predetermined pattern on a resist filmformed on a substrate, and a pattern shape measuring section configuredto measure a shape of a resist pattern and a shape of an etched patternby means of a scatterometory technique, wherein the programinstructions, when executed by the computer, control the apparatus toperform a method comprising: forming a resist film on an etching targetlayer disposed on a test substrate, and performing sequential lightexposure with a predetermined test pattern on the resist filmsequentially at a plurality of areas, while respectively using differentcombinations of a light exposure amount and a focus value, along withsubsequent development, thereby forming resist patterns at the pluralityof areas; measuring shapes of the resist patterns at the plurality ofareas by means of a scatterometory technique; etching the etching targetlayer by use of the resist film with the resist patterns formed thereonas an etching mask, and removing the resist film from the substrate,thereby forming etched patterns at the plurality of areas; measuringshapes of the etched patterns at the plurality of areas by means of ascatterometory technique; and determining a management span ofcombinations of a light exposure amount and a focus value admissible toobtain an etched pattern with a predetermined shape, with reference tothe combinations of a light exposure amount and a focus value used inthe sequential light exposure for the plurality of areas, measurementresults of the shapes of the resist patterns formed at the plurality ofareas, and measurement results of the shapes of the etched patternsformed at the plurality of areas. 12: The computer readable mediumaccording to claim 11, wherein the method further comprises: determiningone combination of a light exposure amount and a focus value within themanagement span after determining the management span; forming a resistfilm on an etching target layer disposed on a product substrate, andperforming light exposure with a predetermined product pattern on theresist film, while using the combination of a light exposure amount anda focus value thus determined, along with subsequent development; andetching the etching target layer and removing the resist film, therebyforming an etched pattern; measuring a shape of the etched pattern bymeans of a scatterometory technique; judging whether or not the shape ofthe etched pattern is within a predetermined admissible dimension range;and, if the shape of the etched pattern is out of the admissibledimension range, determining a new combination of a light exposureamount and a focus value within the management span such that a shape ofan etched pattern to be formed on another product substrate subsequentlyprocessed is brought into the admissible dimension range. 13: Thecomputer readable medium according to claim 11, wherein the methodfurther comprises: determining one combination of a light exposureamount and a focus value within the management span after determiningthe management span; forming a resist film on an etching target layerdisposed on a product substrate, and performing light exposure with apredetermined product pattern on the resist film, while using thecombination of a light exposure amount and a focus value thusdetermined, along with subsequent development; and etching the etchingtarget layer and removing the resist film, thereby forming an etchedpattern; measuring a shape of the etched pattern by means of ascatterometory technique; judging whether or not the shape of the etchedpattern is within a predetermined admissible dimension range; if theshape of the etched pattern formed on the product substrate is out ofthe predetermined admissible dimension range, and a new combination of alight exposure amount and a focus value, determined such that a shape ofan etched pattern to be formed on another product substrate subsequentlyprocessed is brought into the admissible dimension range, is out of themanagement span, performing light exposure with the product pattern onsaid another product substrate, while using the new combination of alight exposure amount and a focus value thus determined, along withsubsequent development; and measuring a shape of a resist patternthereby obtained; if the shape of the resist pattern is within apredetermined dimension range, determining a new management span ofcombinations of a light exposure amount and a focus value, withreference to a target dimension of the test pattern, the shapes of theresist patterns formed on the test substrate, and the combinations of alight exposure amount and a focus value used in the sequential lightexposure; and, if the shape of the resist pattern is out of apredetermined dimension range, re-executing a series of processes todetermine a new management span of combinations of a light exposureamount and a focus value, while using a new test substrate. 14: A lightexposure condition setting method comprising: forming a resist film onan etching target layer disposed on a test substrate, and performingsequential light exposure with a predetermined test pattern on theresist film sequentially at a plurality of areas, while respectivelyusing different combinations of a light exposure amount and a focusvalue, along with subsequent development, thereby forming resistpatterns at the plurality of areas; measuring shapes of the resistpatterns at the plurality of areas by means of a scatterometorytechnique; forming a resist film on an etching target layer disposed ona product substrate, and performing light exposure with a predeterminedproduct pattern on the resist film, while using a predeterminedcombination of a light exposure amount and a focus value, along withsubsequent development, etching, and resist film removal, therebyforming an etched patterns; and measuring shapes of the etched patternsby means of a scatterometory technique; and, if the etched patternsinclude an etched pattern at an area with a shape out of an admissibledimension range, changing the combination of a light exposure amount anda focus value used for performing light exposure on a product substrate,such that shapes of all etched patterns are brought into the admissibledimension range, with reference to the combinations of a light exposureamount and a focus value used in the sequential light exposure for theplurality of areas on the test substrate and measurement data of theshapes of the resist patterns formed on the test substrate. 15: Thelight exposure condition setting method according to claim 14, wherein anew combination of a light exposure amount and a focus value is appliedto an area with a shape of an etched pattern out of the admissibledimension range, and a preceding combination of a light exposure amountand a focus value is applied to an area with a shape of an etchedpattern within the admissible dimension range. 16: A substrateprocessing apparatus comprising: a light exposure processing sectionconfigured to perform light exposure with a predetermined pattern on aresist film formed on an etching target layer disposed on a substrate; apattern shape measuring section configured to measure a shape of aresist pattern and a shape of an etched pattern by means of ascatterometory technique; and a control section configured to controlthe light exposure processing section and the pattern shape measuringsection, wherein the control section makes reference to: a result ofperforming sequential light exposure with a predetermined test patternon a resist film formed on a test substrate, sequentially at a pluralityof areas, while respectively using different combinations of a lightexposure amount and a focus value, along with subsequent development,thereby forming resist patterns at the plurality of areas, and thenmeasuring shapes of the resist patterns at the plurality of areas by thepattern shape measuring section; the combinations of a light exposureamount and a focus value used in the sequential light exposure for theplurality of areas; and a result of performing light exposure with apredetermined product pattern on a resist film formed on an etchingtarget layer disposed on a product substrate, while using apredetermined combination of a light exposure amount and a focus value,along with subsequent development, etching, and resist film removal,thereby forming an etched patterns; and measuring shapes of the etchedpatterns by the pattern shape measuring section, if the etched patternsinclude an etched pattern at an area with a shape out of an admissibledimension range, and when the control section changes the combination ofa light exposure amount and a focus value used for performing lightexposure on a product substrate, such that shapes of all etched patternsare brought into the admissible dimension range. 17: The substrateprocessing apparatus according to claim 16, wherein the control sectionis arranged such that a new combination of a light exposure amount and afocus value is applied to an area with a shape of an etched pattern outof the admissible dimension range, and a preceding combination of alight exposure amount and a focus value is applied to an area with ashape of an etched pattern within the admissible dimension range. 18: Acomputer readable medium containing program instructions for executionon a processor used for a substrate processing apparatus, whichcomprises a light exposure processing section configured to performlight exposure with a predetermined pattern on a resist film formed on asubstrate, and a pattern shape measuring section configured to measure ashape of a resist pattern and a shape of an etched pattern by means of ascatterometory technique, wherein the program instructions, whenexecuted by the computer, control the apparatus to perform a methodcomprising: forming a resist film on an etching target layer disposed ona test substrate, and performing sequential light exposure with apredetermined test pattern on the resist film sequentially at aplurality of areas, while respectively using different combinations of alight exposure amount and a focus value, along with subsequentdevelopment, thereby forming resist patterns at the plurality of areas;measuring shapes of the resist patterns at the plurality of areas bymeans of a scatterometory technique; forming a resist film on an etchingtarget layer disposed on a product substrate, and performing lightexposure with a predetermined product pattern on the resist film, whileusing a predetermined combination of a light exposure amount and a focusvalue, along with subsequent development, etching, and resist filmremoval, thereby forming an etched patterns; and measuring shapes of theetched patterns by means of a scatterometory technique; and, if theetched patterns include an etched pattern at an area with a shape out ofan admissible dimension range, changing the combination of a lightexposure amount and a focus value used for performing light exposure ona product substrate, such that shapes of all etched patterns are broughtinto the admissible dimension range, with reference to the combinationsof a light exposure amount and a focus value used in the sequentiallight exposure for the plurality of areas on the test substrate andmeasurement data of the shapes of the resist patterns formed on the testsubstrate. 19: The computer readable medium according to claim 18,wherein a new combination of a light exposure amount and a focus valueis applied to an area with a shape of an etched pattern out of theadmissible dimension range, and a preceding combination of a lightexposure amount and a focus value is applied to an area with a shape ofan etched pattern within the admissible dimension range.